The objective of the research project is to develop Laser Doppler Velocimetry as a non-invasive technique for the measurement of blood flow at discrete sites in the human ocular fundus. Blood flow through a cross-section of a retinal vessel is the product of the cross-sectional area and the average speed of the flowing blood. The average speed of the flowing red blood cells may be determined from measurements of the Doppler-shift frequency spectrum of laser light scattered back out of the eye. The scattered light has a range of vibrational frequencies that are shifted away from the incident laster light frequency by amounts that are directly proportional to the speeds of the red cells which are primarily responsible for the scattering. The absolute speeds can be determined if the relative angular orientation of the incident and scattered light beams with the flow direction are known. It is expected that as a result of the development of this technique, blood flow measurements could be made with relative ease in the course of the diagnosis and treatment of patients suffering from ocular or systemic disease in which retinal blood flow is altered. BIBLIOGRAPHIC REFERENCE: Riva. C.E., Feke, G.T., and Loebl, M. Laser Doppler measurement of blood flow in the fundus of the human eye. Proceedings of Electro-Optics Laser 1976, Sept. 14-16, 1976, New York, New York, in press.